You can contact CJ for a copy of the manual, they will be more than happy to answer any questions. But if I remember correctly the PV-10A does invert polarity which means if you have an odd number of invertions you must reverse your speaker leads. If the unit is line stage only which is designated by the (L) it has no phono stage then there are only two tubes inside. You can acquire access to the tubes by removing the top cover. If you go to the CJ web site there should be information there as to what type of tube is in the unit. Hope this helps
Chuck
Chuck